She said: “It’s very difficult to do my job without occasionally flying, although I do fly a lot less than I did.

“But we are caught because to travel at all by aeroplane is impossible without causing damage to the planet.

“I’m in the very fortunate position of being able to offset my carbon footprint, but most people can’t.”

The 60-year-old, whose credits include Sense And Sensibility and Love Actually, went on: “We should all fly less. We’re all going to have to fly less.

“It will be inevitable in our lives because we cannot continue to use fossil fuels in the way that we have been doing. It’s very difficult to let go of, it’s a bit like smoking actually.

“We do now know that fossil fuels are threatening the future of the planet so yes it’s unhappy and an inconvenience and indeed we’re often involved in situations where we will be hypocritical but if we don’t address this we are failing our children and our grandchildren.

“The future of this planet is at stake and that’s perhaps more important than our own reputations.”

Asked if she is tempted to go into politics, Dame Emma replied: “Oh god no”.